Consumer electronics requires low power-consumption and high density non-volatile memory. In order to eliminate the sneak path and reduce the power consumption, a selector device is needed for each memory cell, for example, resistive random access memory (RRAM) cell.
Currently, there are several candidate selector devices available, such as Ovonic Threshold Switch (OTS), Mott effect switch based selector devices (NbO2 and VO2), and Mixed-Ionic-Electronic-Conduction (MIEC) material based selector devices. MIEC based selector device and OTS show overlapping curves between the forward voltage sweep and backward voltage sweep. A partial reset might occur because of the voltage-drop competition between the selector device and the memory device. Furthermore, the read voltage and set/reset voltage are required to be greater than the switching voltage of the selector device, which will result in high power consumption. In order to overcome these issues, a selector device with a low on-state holding voltage (Vhold) is desired. Mott effect selector devices exhibit this holding voltage effect, but the hysteresis window is not big enough and also shows a high half-select leakage current. As the size of a memory cell array increases, large amount of leakage current exists, which will cause high power consumption and constraint the development of higher density memory cell array. Accordingly, it is desired to lower the sneak current.
It is desired to provide high performance selectors for a memory device.